Saudi Arabia had a crazy weekend that upended the Middle Eastern kingdom

Saudi Arabia over the weekend experienced upheaval in both internal affairs and external relations.

At the center of the changes is Crown Prince Mohammed bin Salman.

At least 11 princes and dozens of government ministers were arrested in a surprise anti-corruption purge launched Saturday by Salman.

Separately, a prominent member of the royal family died in a helicopter crash.

Saudi Arabia over the weekend saw the arrests of leading government officials and business figures, as well as increased tension with the kingdom's rival Iran.

At the center of the changes is Crown Prince Mohammed bin Salman, the next in line to the Saudi throne. Crown Prince Mohammed — the son of King Salman, who appointed him crown prince in June — has been publicly pushing for economic modernization for the kingdom and recently said he would lead the country back to "moderate Islam."

"With the weekend detentions, Crown Prince Mohammad bin Salman has succeeded in controlling all three Saudi security services, while cowing both conservative and reform-minded clerics — an unprecedented consolidation of power in the country's history," The Soufan Center, a strategic consultancy firm, wrote in a Monday note.

The Financial Times also described the events of the weekend as a purge done as part of Crown Prince Mohammed's consolidation of power, noting that it took place days after he hosted a global development conference dubbed "Davos in the Desert" that seems to be part of the crown prince's global investment push.

Here's what you need to know about Saudi Arabia's ground-shaking weekend:

A purge of princes and ministers

Saturday's arrests hit at the heart of Saudi Arabia's government and business communities.

Among the royals arrested were Prince Alwaleed bin Talal, a billionaire investor, and Prince Miteb bin Abdullah, who was the head of the National Guard.

Talal, who has invested in US companies such as Twitter and Citigroup, owns the investment firm Kingdom Holding and is one of the world's wealthiest men.

As the head of the National Guard, Abdullah oversaw the protection of the royal Saud family, as well as important religious, oil, and gas sites.

By replacing Abdullah, Crown Prince Mohammed sidelined a powerful rival. It appears that in addition to his role as defense minister, he will now have indirect control over the head of National Guard and the interior minister, who oversees internal security.

Crown Prince Mohammed also replaced the minister of economy and planning and the commander of Saudi Naval Forces.

The ousted princes and ministers are being held at the Ritz-Carlton hotel in the capital city of Riyadh. The government said over the weekend that the anti-corruption committee headed by Crown Prince Mohammed had the right to issue arrest warrants, impose travel restrictions, and freeze bank accounts.

But there's been little transparency about the specific reasons behind the arrests.

From left: the new National Guard chief, Khalid bin Ayyaf al-Muqrin; Saudi Arabia's King Salman; and the new economy and planning minister, Mohammed al-Tuwaijri.
Saudi Press Agency, via AP

A deadly helicopter crash

Hundreds of miles southwest of Riyadh on Sunday, a prominent member of the Saudi royal family died when his helicopter crashed during a tour of coastal projects.

Prince Mansour bin Muqrin, the recently named deputy governor of Saudi Arabia's Asir province, was the son of Prince Muqrin bin Abdulaziz, who was at one point the crown prince.

Seven other government officials were reportedly killed in the crash.

The Saudi government has not given a reason for the crash but said a search of the wreckage was underway, according to The Associated Press. Reports have noted that the crash site is about 100 miles from Yemen, where Saudi Arabia has been fighting Houthi rebels since March 2015.

Tensions rise with Iran

Aside from the internal upheaval in the kingdom, this weekend also highlighted rising tensions with Saudi Arabia's regional rival Iran.

Lebanese Prime Minister Saad Hariri — a dual Lebanese-Saudi citizen — resigned on Saturday during a trip to Saudi Arabia. Hariri is part of a joint government that includes Hezbollah, the Iran-backed militant group, and he used his resignation speech to criticize that group and Iran.

After Hariri's resignation, one member of Lebanon's Parliament told CNN, "We are back to an escalation between Iran and Saudi Arabia on the Lebanese front."

The same day, Saudi Arabia said it intercepted a ballistic missile targeting King Khalid International Airport in Riyadh that was launched by Iran-backed Houthi rebels in Yemen.

Saudi Arabia's foreign minister tweeted on Monday that the kingdom reserved the right to respond to Iran's "hostile actions."

A Saudi-led military coalition announced Monday it would close all air, land, and sea ports to Yemen, a move it said would lessen the flow of arms from Iran to the Houthi rebels — though it may also worsen a humanitarian crisis in Yemen.